1. Technical Field
The present invention relates to a projector.
2. Related Art
Hitherto, a reflection type projector has been known as one of the liquid crystal projectors (for example, see JP-A-2004-46156). For example, the reflection type projector includes an illumination optical system, a wire grid element, a reflection type liquid crystal panel, and a projection optical system.
Light emitted from the illumination optical system is incident on a liquid crystal panel via a polarization separating element. The light incident on the liquid crystal panel is modulated and reflected by the liquid crystal panel. The light reflected by the liquid crystal panel is incident again on the polarization separating element and is separated into polarized light for showing an image and polarized light for showing a reversed image. The projection optical system projects the polarized light for showing the image to a screen or the like to display the image.
In some cases, the reflection type liquid crystal panel is configured to include a vertical alignment mode (hereinafter, referred to as a VA mode) liquid crystal layer advantageous to improve a contrast ratio. In the VA mode liquid crystal layer, a pretilt is given in a predetermined direction so as to have an alignment property in many cases. When the pretilt is given in the liquid crystal layer, disclination can be prevented from occurring. However, refractive index anisotropy may occur in the liquid crystal layer when no electric field is applied.
To remove the refractive index anisotropy, an optical compensation plate may be provided in addition to the liquid crystal layer so that the refractive index becomes isotropic. Further, a technique has been suggested to reduce the refractive index anisotropy of the liquid crystal layer when no electric field is applied (for example, JP-A-2007-212997). In JP-A-2007-212997, in a liquid crystal panel in which a liquid crystal layer is interposed between a pair of substrates, the alignment axis of the liquid crystal layer is different at one and the other of the pair of substrates.
In the projector, the contrast ratio is expected to be newly improved, and thus the projector with the above-described configuration can be allowed to be improved. For example, in the liquid crystal panel, the alignment axis of the liquid crystal layer may sometimes be deviated from a predetermined direction due to a manufacture error or the like. When the alignment axis of the liquid crystal layer is deviated from the predetermined direction, a rotational angle between the optical axis of a polarizing plate, a wire grid element, or the like and the alignment axis of the liquid crystal layer may be deviated from a predetermined rotational angle. As a result, a ratio of the polarized light, which is included in the light projected by the projection optical system, for showing a reverse image may be increased, thereby deteriorating the contrast ratio of the projected image.